Question: Solve for $x$ and $y$ using substitution. ${3x-6y = 6}$ ${y = x+1}$
Answer: Since $y$ has already been solved for, substitute $x+1$ for $y$ in the first equation. ${3x - 6}{(x+1)}{= 6}$ Simplify and solve for $x$ $3x-6x - 6 = 6$ $-3x-6 = 6$ $-3x-6{+6} = 6{+6}$ $-3x = 12$ $\dfrac{-3x}{{-3}} = \dfrac{12}{{-3}}$ ${x = -4}$ Now that you know ${x = -4}$ , plug it back into $\thinspace {y = x+1}\thinspace$ to find $y$ ${y = }{(-4)}{ + 1}$ $y = -3$ You can also plug ${x = -4}$ into $\thinspace {3x-6y = 6}\thinspace$ and get the same answer for $y$ : ${3}{(-4)}{ - 6y = 6}$ ${y = -3}$